1. Field of the Invention
The present invention relates to a spindle motor.
2. Description of the Related Art
A small-sized spindle motor used for a hard disk drive (HDD) generally includes a hydrodynamic bearing assembly. This hydrodynamic bearing assembly is provided with a bearing clearance so that a lubricating fluid may be filled therein.
In addition, at the time of the rotation of a shaft, the lubricating fluid filled in the bearing clearance may be pumped to form fluid dynamic pressure, thereby rotatably supporting the shaft.
Meanwhile, the hydrodynamic bearing assembly may include a sealing cap allowing an interface between the lubricating fluid and air to be formed in order to suppress leakage of the lubricating fluid.
That is, the sealing cap serves to form the interface (that is, a liquid-vapor interface) between the lubricating fluid and the air so that the lubricating fluid is not leaked due to a capillary phenomenon in a normal driving state of the spindle motor.
However, when an external impact occurs, the lubricating fluid may be leaked, from a side at which the liquid-vapor interface is formed, to the outside. When the lubricating fluid is leaked to the outside as described above, an inner portion of the spindle motor may be polluted by the lubricating fluid.
In addition, when the lubricating fluid is leaked, the fluid dynamic pressure generated by the pumping of the lubricating fluid may be deteriorated, such that ultimately, the performance of the spindle motor is deteriorated.
Further, a lifespan of the spindle motor may be shortened due to the leakage of the lubricating fluid.